Product Core Brief

• Model: CI853K01, OEM Article Code 3BSE018103R1
• Brand: ABB Control Systems
• Series: CEX Bus communication module for AC800M / System 800xA Controllers
• Core Function: Dual independent isolated serial communication interface; connects AC800M to third-party PLC, variable frequency drives, legacy SCADA, remote panels via RS232/RS422/RS485, supports Modbus RTU master, COMLI, Siemens 3964R and custom ASCII serial protocolsABB.
• Product Type: Slide-in CEX bus communication module, paired with dedicated TP853 DIN rail termination base
• Key Specs: Dual fully isolated serial channels | RS232 / RS422 / RS485 software selectable | Modbus RTU master only | Hot-swap certified | 500 V optical isolation per portNote: Active OEM spare, new original surplus stock available; no serial line redundancy support, exclusively Modbus RTU master mode (slave unsupported)ABB.

Key Technical Specifications

• Power supply: Powered via AC800M rack internal CEX backplane, power consumption 2–5 W typical
• Serial channel quantity: Two fully independent, galvanically separated serial ports
• Hardware interface per channel: Software configurable RS232C, RS422, RS485 half-duplex
• Baud rate range: 75 bit/s ~ 19200 bit/s adjustable in Control Builder M
• Supported serial protocols:
  1. Modbus RTU (Master only, FC01~FC16 standard function codes)
  2. ABB COMLI inter-controller serial protocol
  3. Siemens 3964R point-to-point serial
  4. User-defined custom ASCII serial communication
• Isolation: Each serial port features 500 VAC optical isolation between field wiring and CEX controller logic
• Data bit/parity restrictions: Invalid config combinations prohibited – 7bit-no-parity-1stop / 8bit-parity-2stop cannot be usedABB Group
• Hot swap: Officially IEC certified hot-swap capable while controller rack powered
• PCB coating: ISA-S71.04 G3 grade conformal coating for corrosive industrial cabinet environmentsABB
• Status indicators: Front multi-color LEDs: PWR, CEX RUN, CH1 COM, CH2 COM, HARDWARE FAULT
• Mechanical form: Slide-in card for TP853 DIN rail termination base; IP20 enclosure rating
• Operating ambient: 0 °C ~ +55 °C continuous duty; compact vertical racks limited to 0 ~ +40 °C
• Storage range: -40 °C ~ +70 °C, non-condensing relative humidity 5–95 %ABB Group
• Certifications: CE, UL508, ATEX II 3G Ex nA IIC T4 Gc Zone 2, cULus Class I Div 2; marine DNV/ABS certifiedeero
• Physical dimensions (module+TP853 base): W59 mm × H185 mm × D127.5 mm; total weight 0.55 kgABB Group

Product Introduction

CI853 is a dual serial gateway expansion module for AC800M DCS controllers, plugging into the controller rack’s CEX expansion bus to add two isolated serial channels for third-party device integrationABB.Each channel independently switches between RS232, RS422, RS485 without hardware jumper modification, widely used to connect ABB ACS series drives, old brand PLC, remote serial HMI and legacy Modbus RTU field equipment. Optical isolation eliminates ground-loop noise from long serial trunk cables and VFD EMI interference, preventing serial frame loss or communication freeze.It supports multiple industry standard serial protocols to unify heterogeneous device data into the 800xA DCS database; hot-swap design enables module replacement without full controller shutdown, minimizing production downtime for serial-linked auxiliary equipment.

QA & Testing SOP (Transparency Building)

1. Incoming Inspection: Cross-reference serial numbers and 3BSE part code against ABB AC800M spare databases. Inspect TP853 terminal block pin integrity, dual serial port isolation circuit continuity, full LED bank functionality and intact factory anti-static packaging to filter counterfeit stock.
2. Live Testing: Install CI853 onto TP853 base inside AC800M test rack paired with PM865 CPU simulator. Run continuous 24-hour cyclic serial communication testing on both channels simultaneously: Modbus RTU slave simulator, COMLI secondary controller, 3964R PLC simulator, while logging stable CEX backplane supply via Fluke 115 multimeter. Simulate serial cable short-circuit, baud rate mismatch and port disconnection to validate fault LED flag timing and automatic channel reset behavior.
3. Electrical Testing: Use 500V Megger to measure optical isolation resistance per serial channel vs CEX bus logic; pass threshold ≥10 MΩ. Inject 50Hz differential ground-loop noise to confirm no serial frame corruption or random communication dropouts.
4. Firmware/Config Backup: Record factory default serial baud rate, protocol and wiring mode preset values via Control Builder M engineering software. Capture high-resolution photos of TP853 terminal pinout and channel wiring layout for field commissioning reference.
5. Final QC & Packaging: Fit plastic dust caps over dual serial terminal ports, match supporting base accessory kit. Place module inside foam-lined anti-static shielding bag, affix a dated QC pass label before sealing in original factory carton.

Installation Pitfalls & Guide (Engineer to Engineer)

❗Firmware Rev Mismatch Risk: controller firmware older than v5.0.8 lacks CEX register mapping for dual-channel parallel serial polling logic. Post-replacement, only one serial channel operates normally and throws intermittent SERIAL COMM LOSS alarms. Remediation: Flash matching firmware revision to PM865 CPU before inserting module onto base.❗Serial Wiring Topology Risk: RS485 multi-drop trunk requires end termination resistor only on the farthest slave device; duplicate termination or missing resistor causes signal reflection, persistent communication jitter and random slave offline faults.❗Modbus Mode Limitation Risk: CI853 only supports Modbus RTU master mode; cannot act as Modbus slave. If the site requires DCS to respond to external master requests, additional CI854/CI867 Ethernet modules are required.❗Invalid Serial Parameter Risk: Two specific serial format combinations are hardware unsupported (7N1 / 8P2). Configuring these in Control Builder M creates permanent channel communication fault codes with no data exchangeABB Group.❗ESD Dangers: Ungrounded handling exposes dual serial transceiver and CEX bus logic traces to static discharge from dry control room air. Field records show unprotected handling burns both serial channels simultaneously; full auxiliary equipment downtime labor cost exceeds $1,480. Remediation: Place anti-static mat under controller rack, wear grounded wrist strap, touch bare cabinet chassis ground for 3 seconds before handling module.

4-step replacement guide

1. Pre-install: Pause all serial communication logic blocks in Control Builder M to stop Modbus/COMLI polling; CI853 supports hot-swap, but record CH1/CH2 wiring layout, baud rate and protocol configuration before extraction.
2. Removal: Unlatch base retention clip, slide CI853 upward out of base slot, disconnect dual serial terminal block wiring and store unit in static-safe sleeve.
3. Install: Insert new fully into base and lock retention latch; reconnect serial trunk wiring to matching channel terminal positions, install RS485 end termination resistor on far-end slave if multi-drop topology.
4. Power-on Test: Controller rack remains powered (hot-swap permitted); verify front CH1/CH2 COM LEDs illuminate steady green, run full serial device scan on both channels to confirm stable data exchange before re-enabling automatic DCS serial polling logic.

FAQ

Q: Can be hot-swapped while the controller rack remains powered?A: Yes, carries official ABB hot-swap certification for standard control room environments. No full rack power isolation required for replacement, only pause serial polling logic beforehand to avoid temporary device data loss.

Q: Does this serial communication module carry original OEM factory warranty when purchased as new surplus?A: ABB factory warranty follows standard component lifecycle coverage. All surplus inventory passes full in-house bench QA testing and carries a 12-month internal stock replacement warranty, limited to manufacturing defects detected during validation testing.

Q: Can CI854B serve as a direct functional replacement for ?A: Mechanical CEX slot fit compatible, but function completely different: CI854B is PROFIBUS DP-V1 master module for S800 I/O, without any serial RS232/485 hardware. Swapping CI854B cannot realize Modbus RTU serial communication and requires full bus architecture rework.

Q: What minimum CPU firmware version enables full dual-channel parallel serial polling support?A: PM86x controller firmware v5.0.8 or newer. Older firmware only initializes one serial channel and cannot execute simultaneous Modbus + COMLI communication on separate ports.

Q: Will serial baud rate, protocol and wiring mode configuration persist after module replacement?A: All serial channel configuration data resides in CPU non-volatile memory; no local parameter storage on hardware. No full reconfiguration required post-swap, only serial device scan verification for both channels.

Q: Is compatible with legacy Advant AC450 / MasterPiece DCS racks?A: No. uses modern CEX expansion bus architecture, with zero electrical and mechanical compatibility with Advant AC450 CEX bus CI54x communication modules.

Q: Can multiple Modbus RTU slave devices be multi-dropped on a single channel?A: Yes, each channel supports up to 32 Modbus RTU slave nodes under master mode operation, as long as correct end-of-line termination resistor is fitted on the last slave device of the trunk line.